1. Field of the Invention
This invention relates to a volume controller for balancing the sound volume between a front speaker which is located at the front of a vehicle and a rear speaker which is located at the rear of the vehicle.
2. Description of the Related Art
Traditionally, an audio device has been widely used which is provided with four speakers on the left and right sides at the front and the rear within a vehicle, respectively in order to cause a driver/passenger to hear the signal reproduced from a broadcast, CD, DVD, etc.
Such an in-vehicle audio device can regulate the volume balance in a to-and-fro direction. In this case, as shown in FIG. 3, where a balancing point is moved from the center to the front side by an fade input from a fader inputting unit the volume from the front speaker does not vary whereas the volume from the rear speaker decreases with the fade input. If the balancing point is moved from the center toward the rear side, the volume from the rear speaker does not vary whereas the volume from the front speaker decreases with the fader input.
The volume balancing regulation having such a characteristic has the following disadvantage. Where a passenger who sits on the rear seat of a one-box car enjoys, a movie using a DVD player, which is now prevailing, using a rear speaker as a main speaker, he or she balances the volume from a center position to the rear side. However, actually, the volume decreases only at the front. It lacks the spreading toward the front at the listening point, and the volume within an entire room varies (decreases). This makes it difficult to form a sound field with a sense of realism.